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Cathar · 08-20-2004, 05:13 AM

Les, thanks for the graphs.

My thinking was as follows:

For the 300x240x29mm radiator I was personally approximating fairly close to a 10Pa drop at 3m^3/min, or for 160x160x25mm, around about 1.25m^3/min at 10Pa, or about 6.5Pa at 1m^3/min. So maybe 1.1m^3/min with the Papst.

C/W of air at 1.1m^3/min ~= 0.044

Bill's tests of the Thermochill 120.2 appear to imply a radiator efficiency in the very high 90's percent for air-flow rates of less than 1.0m^3/min and flow rates of at least 1gpm.

Assuming radiator efficiency of 90% @ 1.1m^3/min => C/W of 0.048-0.049

Ultimately it comes down to whether or not I was right with the 10Pa @ 3m^3/min assumption/extrapolation in the first place though. Core is thinner and less densely finned than the Thermochills, so I applied some extrapolation there to arrive at the large radiator's pressure drop by using Bill's PQ graph for the 120.2. Bill suggested 10Pa for the 120.2 at 1m^3/min. 2.5x the surface area immediately implies 2.5m^3/min at 10Pa, and I applied an arbitrary 20% bonus due to the more free-air flowing characteristics of this radiator.

08-20-2004, 05:13 AM	#85
Cathar Thermophile Join Date: Sep 2002 Location: Melbourne, Australia Posts: 2,538	Les, thanks for the graphs. My thinking was as follows: For the 300x240x29mm radiator I was personally approximating fairly close to a 10Pa drop at 3m^3/min, or for 160x160x25mm, around about 1.25m^3/min at 10Pa, or about 6.5Pa at 1m^3/min. So maybe 1.1m^3/min with the Papst. C/W of air at 1.1m^3/min ~= 0.044 Bill's tests of the Thermochill 120.2 appear to imply a radiator efficiency in the very high 90's percent for air-flow rates of less than 1.0m^3/min and flow rates of at least 1gpm. Assuming radiator efficiency of 90% @ 1.1m^3/min => C/W of 0.048-0.049 Ultimately it comes down to whether or not I was right with the 10Pa @ 3m^3/min assumption/extrapolation in the first place though. Core is thinner and less densely finned than the Thermochills, so I applied some extrapolation there to arrive at the large radiator's pressure drop by using Bill's PQ graph for the 120.2. Bill suggested 10Pa for the 120.2 at 1m^3/min. 2.5x the surface area immediately implies 2.5m^3/min at 10Pa, and I applied an arbitrary 20% bonus due to the more free-air flowing characteristics of this radiator. Last edited by Cathar; 08-20-2004 at 05:19 AM.